October 25, 2004

Deleting junk DNA in mice

Researchers deleted large portions of junk DNA from the mouse genome and created mice with the altered genome. No adverse effects were detected, indicating that perhaps non-coding DNA may in fact be useless.

Nature 431, 988 - 993 (21 October 2004); doi:10.1038/nature03022

Megabase deletions of gene deserts result in viable mice

MARCELO A. NÓBREGA et al.

The functional importance of the roughly 98% of mammalian genomes not corresponding to protein coding sequences remains largely undetermined1. Here we show that some large-scale deletions of the non-coding DNA referred to as gene deserts2-4 can be well tolerated by an organism. We deleted two large non-coding intervals, 1,511 kilobases and 845 kilobases in length, from the mouse genome. Viable mice homozygous for the deletions were generated and were indistinguishable from wild-type littermates with regard to morphology, reproductive fitness, growth, longevity and a variety of parameters assaying general homeostasis. Further detailed analysis of the expression of multiple genes bracketing the deletions revealed only minor expression differences in homozygous deletion and wild-type mice. Together, the two deleted segments harbour 1,243 non-coding sequences conserved between humans and rodents (more than 100 base pairs, 70% identity). Some of the deleted sequences might encode for functions unidentified in our screen; nonetheless, these studies further support the existence of potentially 'disposable DNA' in the genomes of mammals.

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